Process for the manufacture of catalyst members for the reduction of oxides of nitrogen and catalyst members produced thereby

Abstract

This invention relates to a process for the manufacture of catalysts for the reduction of oxides of nitrogen from exhaust gases and in chemical air cleaning processes in which a catalytically active material containing iron ores, chromium ores and/or zeolite is placed in contact with a carrier means having a series of openings; e.g., wire mesh, expanded or perforated metal or any type of grid-like structure to form a catalytic member. The carrier means is etched with an acid etchant before forming the catalytic member or, instead, the catalytic member is etched with an acid etchant. The catalytic member is bonded by a thermal treatment; e.g., drying, tempering and/or fixing. This invention also relates to catalytic members or products produced by the process. This invention proposes the use of pressure bonding to obtain a catalytic member product which has significantly improved catalytic activity, greater mechanical strength and higher resistance to chipping.

What is claimed is: 
     
       1. Process for the production of a catalytic member having a catalytically active material and a carrier means comprising the steps of: etching the carrier means with an acid etchant;   contacting the carrier means with the catalytically active material and applying sufficient pressure to the carrier means and the catalytically active material while they are in contact to form a mechanically bonded composite body.   
     
     
       2. The process according to claim 1, wherein the pressure applied is at least 0.5 newtons per square millimeter. 
     
     
       3. The process according to claim 1, wherein the pressure applied is 2 to 5 newtons per square millimeter. 
     
     
       4. The process according to claim 2, wherein the catalytically active material is used together with a thermosetting synthetic resin. 
     
     
       5. The process according to claim 4, wherein the thermosetting resin is pulverized phenol novolak resin. 
     
     
       6. The process according to claim 1, wherein the catalytically active material has a grain size of up to 2 millimeters. 
     
     
       7. The process according to claim 6, wherein the catalytically active material contains up to 60% of such material having a grain size of more than 0.5 millimeters. 
     
     
       8. The process according to claim 2, wherein the carrier means is layered on opposing sides with the catalytically active material before applying pressure. 
     
     
       9. The process according to claim 8, wherein the pressure applied is 20 to 80 newtons per square millimeter. 
     
     
       10. The process according to claim 8, wherein the pressure applied is 30 to 60 newtons per square millimeter. 
     
     
       11. The process according to claim 4, wherein the composite body is treated with an acid etchant to etch the carrier means and the catalytically active material. 
     
     
       12. The process according to claim 4, wherein the carrier means is etched with an acid etchant acid prior to contacting with the catalytically active material. 
     
     
       13. Process for the manufacture of a catalytic member for the reduction of oxides of nitrogen which comprises: providing a particulate catalytically active material selected from the group consisting of iron ore, chromium ore, zeolite and combinations thereof;   depositing said catalytically active material on a metal carrier means having openings;   thermally bonding the carrier means to the catalytically active material to form a unitary body;   etching the unitary body with an etchant acid and applying at least 0.5 newtons per square millimeter pressure to the etched unitary body.   
     
     
       14. The process according to claim 13, wherein the carrier means is etched prior to depositing the catalytically active material thereon. 
     
     
       15. The process according to claim 13, wherein the catalytically active material contains from a small but significant amount of catalytically active material to about 60% of such material having a grain size of at least 0.5 millimeters. 
     
     
       16. The process according to claim 13, wherein the pressure applied is 30 to 60 newtons per square millimeter. 
     
     
       17. The process according to claim 13, wherein the carrier means has catalytically active material on two opposing sides. 
     
     
       18. A catalytic member for use in the reduction of oxides of nitrogen comprising a compressed composite body having an etched carrier means with a series of openings sandwiched between two layers of a catalytically active material selected from the group consisting of iron ore, chromium ore, zeolite and combinations thereof.